Aggresive or not??

Hi, how old is your dog? Puppies usually go through a phase when they are prone to doing things aggressively. It may involve biting, nipping or chewing which can be corrected through proper training and follow through. Here is a good read about puppy nipping: www.howtoteachadog.com/how-to-stop-puppy-biting

When she encountered the dogs on her property she probably was going to play with them. But instead she saw their barking as a threat. She was just defending what is hers and you. And in other situation, as hard as it may be, try to trust that your dog will do fine. I was actually in an obedience class with a woman and a heeler and she was always overly nervous that her dog would attack other dogs, and he did. He got my dog twice. In his eyes he was just protecting his owner because he was getting the vibe that she was "nervous or scared" whenever another dog approached. As far as the growling in the car, this can be trained out of her with patience. Form a command like "watch me" and when you pass another dog use the command to take her attention off of the dog and walker and onto you. I hope this is useful information.

testing

Guess I can only post little replies from my phone.....

I am not a trainer, just an old broad with years of experience with dogs of many breeds.

This does not sound like aggression to me so much as not knowing the proper behavior.  As for the car, that sounds almost like she might be resource guarding.

The very BEST advise that anyone can give you is to tell you to find a very good, positive reinforcement trainer.  The trainer will teach YOU how to train your dog, so  don't expect miracles without some work of your own.

I would post my property to keep the tourists from roaming around loose.  Or, if you actually want them there, then keep your dog on a long line and teach her a good, solid "leave it".